The objective of this proposed study is to test the hypothesis that the peristaltic nature of contractions in the esophagus is controlled by the intrinsic nerves and muscle at each level of the organ. The peristaltic sequence does not depend on extrinsic nervous reflexes within either the central or peripheral nervous system. The hypothesis will be tested mainly on the esophagus of the opossum. The opossum esophagus is similar to that of man being composed of a combination of striated and smooth muscle. Contractile and electrical activities at several loci of the esophagus will be monitored both in vivo and in vitro. Results of this study may be expected to increase our knowledge of the control of esophageal peristalsis and may indicate ways to determine the cause and to correct or control various motor abnormalities of the esophagus such as diffuse esophageal spasm and achalasia. In addition, results of this study may suggest new ways to approach the investigation of the control of motility in other areas of the gastrointestinal tract.